Rock drill bit

ABSTRACT

A rock drill bit having helical side cutting edges and radial bottom cutting edges, and having an inside cavity for receiving cooling mud, with diametrically opposite downwardly and outwardly inclined outward passages connecting the inside cavity to diametrically opposite grooves between the side cutting edges. The bottom of the bit has a central mud return passage leading to the inside cavity and provided with a ball check valve.

United States Patent [72] Inventors Joseph W. Powell Bishop, Callt;Juanita Powell, sole helr, Box 18, Placerville, Colo. 81430 [211 App].No. 878,770 [22] Filed Nov. 21, I969 [45] Patented Sept. 28, 1971 [54]ROCK DRILL BIT 6 Claims, 4 Drawing Figs.

[52] [1.8. CI 175/237, 173/90, 175/395. 175/418 [51] lnt.C1 E21: 13/06[50] Field olSearch 175/417, 418, 415, 237, 395-,173/90 [56] ReferencesCited UNITED STATES PATENTS 1,057,733 4/1913 Hansen.......... 175/4182,191,699 2/1940 Stephens 175/415 X 2,294,004 8/1942 Serafino 175/419 X2,368,512 [/1945 Zimmerman 175/418 X 2,802,642 8/1937 Feucht 175/418 X3,172,486 3/1965 Kinley 175/237 X 3,195,660 7/1965 MCKoWn 174/237 X3,452,832 7/1969 Ditson 1, 175/418 X Primary Examiner.1ames A. LeppinkAttorney-Berman, Davidson and Berman ABSTRACT: A rock drill bit havinghelical side cutting edges and radial bottom cutting edges, and havingan inside cavity for receiving cooling mud, with diametrically oppositedownwardly and outwardly inclined outward passages connecting the insidecavity to diametrically opposite grooves between the side cutting edges.The bottom of the bit has a central mud return passage leading to theinside cavity and provided with a ball check valve.

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This invention relates to rock-drilling bits, and more particularly torock-drilling bits of the type provided with means for conveyingsuitable flushing liquids to the cutting edges of the bit.

A main object of the invention is to provide a novel and improvedrock-drilling bit which is simple in construction, which is providedwith means for conveying cooling mud or other cooling liquid to thecutting edges thereof, and which is further arranged so that the coolingmud or liquid can circulate through the bottom portion of the drill bitwhile the drill bit is in operation, thereby providing an efficientcooling action.

A further object of the invention is to provide an improvedrock-drilling bit which is inexpensive to manufacture, which is durablein construction, which is economical to use, and which provides aneffective cooling action to its cutting edges so as to maintain suchcutting edges sharp over long periods of use of the bit.

A still further object of the invention is to provide an improvedrock-drilling bit of the type employing circulating cooling mud orsimilar cooling fluid in the region of its cutting edges, the passagesfor circulating the cooling mud for liquid being so arranged as tominimize the possibility of their becoming clogged by rock chips orsimilar debris, whereby the bit can be maintained in an efficientoperating condition over long periods of use.

Further objects and advantages of the invention will become apparentfrom the following description and claims, and from the accompanyingdrawing, wherein:

FIG. 1 is a bottom plan view of an improved rock-drilling bitconstructed in accordance with the present invention;

FIG. 2 is a side elevational view of the rock-drilling bit of FIG. 1;

FIG. 3 is a top plan view ofthe bit of FIG. 1 and 2;

FIG. 4 is a vertical cross-sectional view taken substantially on theline 4-4 of FIG. 3.

In the art of drilling rock, concrete, or the like, it is found to benecessary to supply suitable cooling mud or liquid to a bit employed inthis operation for the purpose of preventing undesirable temperatureeffects from damaging the cutting edges of the drill bit, since theheavy percussion forces applied to the drill bit tends to create highfriction and accompanying high temperature effects. In order toefficiently cool the drill edges and other parts subjected to heavypercussion effects, it is necessary to provide an adequate supply ofcooling mud or liquid thereto, and it is further advantageous to providecirculation of the cooling mud or cooling liquid so as to carry off thegenerated heat rapidly and effectively. In the prior art devices wherecirculation has been attempted, there is a tendency in many designs forthe circulation passages to become clogged up by loose bits of rock orother debris generated by the operation of the drill mechanism. A primepurpose of the present invention is to provide an arrangement whereinthe tendency of the passages to become clogged is reduced to a minimum.

Referring to the drawing, ll generally designates an improved rock drillbit constructed in accordance with the present invention. The drill bit11 comprises a main body 12 having an axial bore provided with internalthreads 13, whereby the body 12 may be threadedly secured in aconventional manner to a suitable hollow drill shank, not shown, throughwhich cooling mud or other cooling liquids, such as a mixture of air andwater, may be conveyed to the drill bit cavity. This cooling mixture isthus furnished to the drill bit cavity and is deposited in the lowerportion 14 thereof.

The body 12 is formed with spirally shaped side cutting teeth 15 whichmerge with radially extending bottom cutting teeth 16, which maycomprise suitable hard metal inserts of tungsten carbide or other highlydurable metal, the inserts being suitably secured in radial cavities 17provided therefor in the bottom portion of the drill bit body 12.

The bottom of the drill bit body 12 is formed with a central recess 18,and said body is further formed with an axial bore 19 communicating withthe bottom portion 14 of the main drill bit cavity through a shortsleeve 20 secured in the top portion of the bore 19, as shown in Figure4. The bottom end of the bore 19 communicates with the central bottomrecess 18 through a reduced passage 21, thereby defining a check valveball cavity 22. A check valve ball 23 is positioned in the cavity andnormally rests on a substantially frustoconical bottom seat 24 providedtherefor around the top end of the reduced passage 21. As will beapparent from FIG. 4, the ball 23 is free to rise in the central checkcavity 19 and thus allows unrestricted flow upwardly through bore 19 andsleeve 20, but prevents downward flow through passage 21.

The body 12 is formed with a pair of diametrically opposite downwardlyand outwardly inclined flow passages 25, 25 connecting opposite grooves26 which are defined between adjacent cutting edges 15, to the bottomspace 14 in the body I2 of the bit. Thus, the cutting edges l5 at thesides of the bit are defined by respective spirally shaped ribs, asabove mentioned, which are of generally triangular cross section, andthe passages 25, 25 open at the troughs between respective adjacentpairs of said spirally shaped portions carrying the side cutting edges15. The passages 25, 25 are downwardly and outwardly inclined,approximately at angles of 45, as shown in FIG. 4.

In operation, suitable cooling liquid or mud, such as a mixtureincluding water and air is forced downwardly through the supportingshank and into the bottom portion l4 of the bit cavity, the coolingmixture flowing outwardly adjacent the cutting edges and impactingsurfaces of the bit through the passages 25, 25. As will be readilyunderstood, the bit is rotated as well as driven downwardly during itsoperation, and the cooling liquid passes downwardly through the grooves26 and beneath the bit, eventually being forced upwardly past the checkvalve ball 23 into the passage 22 and thence through the sleeve 20 backinto the space 14. During operation of the bit this process is repeated,thereby providing circulation of the cooling liquid material andpromoting efficient cooling of the bit so as to prevent an excessiverise in temperature of the cutting edges thereof. The loosened materialis forced upwardly in a conventional manner and removed at the surfaceof the bore hole, and the liquid pressure applied outwardly from thespace 14 resists any tendency for fragments of material to lodge in thepassages 25. It is also not possible for fragments of undesirable sizeto pass upwardly through the restricted passage 21, since said passageis quite small. Thus, the cooling liquid is circulated in an efficientmanner responsive to the reciprocation and accompanying rotary action ofthe drill bit and excessive temperature rise of the cutting edgeportions of the bit is thereby prevented.

The fluid is forced under pressure downwardly through passages 25. Asthe ball 23 vibrates as a result of the impact produced from the actionof the associated percussion drilling machine, the fluid intermittentlyis forced upwardly through passage 22, and therefore, the fluid isintermittently forced downwardly to facilitate drilling and thereafteris forced upwardly to rid the drill hole of cuttings.

It will be understood that with the bit in operation, there will beliquid material in the bore hole, so that with each downward stroke ofthe hit, some of the liquid material will be forced upwardly into thecheck valve cavity 22, and eventually will be forced into the main bitcavity space 14, so that it can be recirculated outwardly through thediametrically opposite side passages 25, 25. This circulation continuesas long as the bit is operated, assuming that an adequate supply ofcooling mud or liquid is furnished to the bit through the hollowsupporting shank.

The ball 23 not only functions as a check valve ball but also as avibratory element, since said ball is of considerable mass, and acts tovibrate the lower portion of the bit so as to shake fragments ofmaterial off the bottom end thereof and prevent such fragments frompassing upwardly through the valve cavity 19. Thus, materials such asclay, or the like, which might tend to thicken and clog in the passages25, 25 of the bit are vibrated off the bottom surface of the bit by therepeated impacts of the ball 23 against the surfaces of its retainingcavity as the bit is reciprocated and rotated during its normaloperation. The impact of the ball 23 against its seat and against theadjacent surfaces of its retaining cavity tends to shake particles ofclay loose from the region adjacent the passage 21 and to cause suchparticles to drop down and away from the recess IS.

The vibratory action of the ball 23 is produced by the shock generatedby the action of the associated percussion drilling machine (the machineforces the steel bit down and the bit stops suddenly as it hits therock, which causes the ball 23 to have a start-stop, or vibratory,action).

In the operation of the bit, it is rotated in a counterclockwisedirection, as viewed in FIG. 3, and the cooling mud or liquiddischarging from the passages 25, 25 flows downwardly and rearwardlythrough the associated grooves 26 toward the regions beneath the radialcutting edge members 16 so as to effectively cool said cutting edges.

From the above description, it will be readily apparent while the drillbit is in operation, the circulating liquid maintains the variouspassages thereof clear and prevents said passages from being clogged bythe clay or the loose material generated by the percussion strokes ofthe bit. Thus, the circulating liquid material provides a self-clearingaction, as well as a cooling action on the drill bit.

While a specific embodiment of an improved rock drill bit has beendisclosed in the foregoing description, it will be understood thatvarious modifications within the spirit of the invention may occur tothose skilled in the art. Therefore, it is intended that no limitationsbe placed on the invention except as defined by the scope of theappended claims.

W hat is claimed is:

l. A rock drill bit comprising a body adapted to be connected to ahollow supporting shank to receive cooling fluid therefrom, said bodyhaving a central cavity and a plurality of side cutting teeth havinggrooves therebetween, respective radial bottom cutting teeth mounted onthe bottom of said body and merging with said side cutting teeth, saidbody being formed at its bottom portion with an axial bore communicatingwith said central cavity, said bore having a centrally apertured bottomwall opening adjacent the inner ends of said radial bottom teeth, saidbody having a plurality of side passages connecting said central cavityto said respective grooves between pairs of side cutting teeth, and avibratory ball member loosely disposed in said axial bore and beingsealingly engageable over the central aperture of said bottom wall,wherein said side cutting teeth are spirally curved, wherein said sidepassages are inclined downwardly and outwardly from said central cavity,wherein said side passages are located diametrically opposite eachother, and wherein said axial bore is provided with stop means limitingupward move ment ofsaid vibratory ball member therein.

2. The rock drill bit of claim I, and wherein said stop means comprisesa sleeve member secured in the upper portion of said axial bore andhaving an inside diameter less than the diameter of the vibratory ballmember.

3. The rock drill bit of claim 1, and wherein said side passages areinclined downwardly and outwardly at an angle of approximately 45 to thehorizontal.

4. The rock drill bit of claim 1, and wherein the bottom wall of theaxial bore is formed with a frustoconical ball seat around said centralaperture.

5. The rock drill bit of claim 1, and wherein the underside of said bodyis formed with a central recess inwardly adjacent the inner ends of theradial bottom teeth, said central aperture opening centrally in saidcentral recess.

6. The rock drill bit of claim 1, and wherein said central cavity of thebody has a frustoconical downwardly convergent bottom wall surface, saidaxial bore merging with said bottom wall surface at the apex portion ofsaid bottom wall surface said side passages opening into the centralcavity at said frustoconica] bottom wall surface.

1. A rock drill bit comprising a body adapted to be connected to ahollow supporting shank to receive cooling fluid therefrom, said bodyhaving a central cavity and a plurality of side cutting teeth havinggrooves therebetween, respective radial bottom cutting teeth mounted onthe bottom of said body and merging with said side cutting teeth, saidbody being formed at its bottom portion with an axial bore communicatingwith said central cavity, said bore having a centrally apertured bottomwall opening adjacent the inner ends of said radial bottom teeth, saidbody having a plurality of sIde passages connecting said central cavityto said respective grooves between pairs of side cutting teeth, and avibratory ball member loosely disposed in said axial bore and beingsealingly engageable over the central aperture of said bottom wall,wherein said side cutting teeth are spirally curved, wherein said sidepassages are inclined downwardly and outwardly from said central cavity,wherein said side passages are located diametrically opposite eachother, and wherein said axial bore is provided with stop means limitingupward movement of said vibratory ball member therein.
 2. The rock drillbit of claim 1, and wherein said stop means comprises a sleeve membersecured in the upper portion of said axial bore and having an insidediameter less than the diameter of the vibratory ball member.
 3. Therock drill bit of claim 1, and wherein said side passages are inclineddownwardly and outwardly at an angle of approximately 45* to thehorizontal.
 4. The rock drill bit of claim 1, and wherein the bottomwall of the axial bore is formed with a frustoconical ball seat aroundsaid central aperture.
 5. The rock drill bit of claim 1, and wherein theunderside of said body is formed with a central recess inwardly adjacentthe inner ends of the radial bottom teeth, said central aperture openingcentrally in said central recess.
 6. The rock drill bit of claim 1, andwherein said central cavity of the body has a frustoconical downwardlyconvergent bottom wall surface, said axial bore merging with said bottomwall surface at the apex portion of said bottom wall surface, said sidepassages opening into the central cavity at said frustoconical bottomwall surface.